Regulator circuits are widely used in integrated circuit designs to provide an internal power supply or supply reference (such as a voltage or current) which, ideally, decouples the external applied power supply voltage (to the first order) as well as load on the supply pins of the chip
A first conventional n-channel replica regulator 20 solution is shown in FIG. 1. The regulator 20 takes a voltage input, and provides two separate voltage outputs for analog and digital logic (outa and outd respectively). This conventional replica architecture 20 may suffer from poor load regulation, as no information about the output voltage is available to the regulator core. The poor load regulations are worse at minimum input voltage levels and load current values.
A second conventional n-channel replica regulator 40 with 1-bit ADC correction is shown in FIG. 2. The 1-bit ADC provides feedback to the resistance stack R1, R2, R3 in the regulator core, performing a coarse correction to the output voltage. In the event where the load current increases, the analog output will fall below the replica reference voltage shown as OUTREF. This will pull comparator output COMP low and introduce extra resistance R1, which in turn will increase replica reference voltage OUTREF and thus increase the output voltages OUTa and OUTb. However, this scenario will cause an abrupt change in output voltage with increasing load current, and will degrade load regulation.
These replica regulators 20, 40 can be stabilized across a large range of output load current and load capacitance. However, these conventional replica regulator implementations 20, 40 can suffer from poor load regulation and poor peak load current capability.
Accordingly, as recognized by the present inventors, what is needed is a regulator circuit that can provide large output load currents without substantially degrading load regulation.
It is against this background that various embodiments of the present invention were developed.